Sheet comber

ABSTRACT

An improved comber assembly for removing sheets one at a time from a pile of sheets includes a reciprocatable pushrod for moving a comber member downwardly into engagement with an upper sheet on the pile of sheets. The comber member is mounted on the free end of a leaf spring which is operatively connected at an opposite end with the pushrod. After the comber member has been brought into engagement with the upper sheet, the spring is deflected by continued downward movement of the pushrod. This deflection of the spring presses the comber member both downwardly and sidewardly to move the upper sheet relative to the next adjacent lower sheet. The sideward movement causes the upper sheet to tend to buckle upwardly so that it is slightly separated from the next adjacent lower sheet.

United States Patent [72] Inventor William H. Weidman 1,225,740 3/1917 Anderson 271/19 I Independence, Ohio 1,460,336 6/1923 Hart 271/20 [2| P 785831 Primary Examiner-Joseph Wegbreit [22] Filed Dec. 23, 1968 A t Y t H & T 451 Patented June 11, 1971 {73] Assignee Harris-lntertype Corporation Cleveland ohm ABSTRACT: An improved comber assembly for removing sheets one at a time from a pile of sheets includes a [54] SHEET COMBER reciprocatabl e pushrod for moving a comber member 8 Claims 5 Drawing Figs downwardly into engagement with an upper sheet on the pile of sheets. The comber member is mounted on the free end of a [52] [1.5. CI 271/19 l af s ring which is operatively connected at an opposite end l B65! with the pushrod. After the comber member has been brought Flald of 24, into engagement the upper heet the spring is deflected 25, 21 by continued downward movement of the pushrod. This deflection of the spring presses the comber member both [56] References Cited downwardly and sidewardly to move the upper sheet relative UNITED STATES PATENTS to the next adjacent lower sheet. The sideward movement 632,268 9/1899 Kershaw 271/25 causes the upper sheet to tend to buckle upwardly so that it is 747,862 12/ 1 903 Dexter et al. 271/19 slightly separated from the next adjacent lower sheet.

PATENTEU JUN 1 l9?! SHEET 1 OF 2 FIGI INVENTOR. WILL/AM H WE/DMAN PATENTED JUN 1197: 5 2,0 4

sum 2 or 2 INVENTOR.

WILL/AM H waomu /4@ BY ATIURNEYJ' SHEET COMBER This invention relates generally to an apparatus for removing sheets one at a time from a pile of sheets and more particularly to a comber assembly for use in separating one sheet from a next adjacent sheet on a pile of sheets.

It is a known practice to use suckers for lifting and feeding sheets one at a time from a pile of sheets. Problems have been encountered due to the suckers drawing air through the upper or top sheet so that suction is applied to the lower sheets. This striking through or penetrating of the top or upper sheet results in more than one sheet being lifted at the same time by the suckers. To prevent a transfer of a plurality of sheets at one time by the suckers, comber assemblies have been used to provide a slight separation between the top sheet and the next adjacent lower sheet at the areas where the top sheet is engaged by the suckers.

These comber assemblies usually include a wheel which is moved into engagement with the upper sheet. The wheel is then rotated to form small buckles or rises in the sheets. The small buckles or rises provide a slight separation at the area where a sucker engages the top sheet. The separation is effective to enable air to enter between the top sheet and the next adjacent lower sheet so that the sucker can lift only one sheet at a time. One known type of comber and sucker arrangement is illustrated in US. Pat. No. 3,076,648 to Taylor.

I-Ieretofore, these known comber assemblies have been somewhat unsatisfactory in their operation due to the formation of shine" marks on the sheets. These shine marks are caused by relative rotation between the comber wheel and the sheet. Thus, during operation of these known comber assemblies, the comber wheel is brought to engagement with a top sheet and is rotated relative to the top sheet to form a slight buckle in the sheet. During this relative rotation, the comber wheel tends to bumish the top sheet and thereby forms the objectional shine marks on the sheet.

Accordingly, it is an object of this invention to provide a new and improved method and apparatus for use in separating one sheet of a pile of sheets from a next adjacent sheet wherein the formation of shine marks on the sheets is eliminated or at least minimized.

Another object of this invention is to provide a new and improved comber assembly for use in feeding sheets one at a time from a pile of sheets wherein the comber assembly includes a comber member which is pressed downwardly and sidewardly against an upper sheet in such a manner as to tend to minimize relative movement between the comber member and the upper sheet.

Another object of this invention is to provide a new and improved comber assembly for use in separating one sheet of a pile of sheets from a next adjacent sheet, wherein the comber assembly includes a comber member and a drive means for pressing the comber member against a sheet and effecting translational movement of the comber member and the engaged portion of the sheet to thereby tend to separate the sheet from a next adjacent sheet on a pile of sheets.

Another object of this invention is to provide a new and improved method of separating an upper sheet of a pile of sheets from a next adjacent sheet wherein the method includes the steps of pressing a comber member against the upper sheet and effecting contemporaneous translational movement of both the engaged portion of the upper sheet and the comber member while retaining the comber member against rotational movement.

These and other objects and features of the invention will become more apparent upon the consideration of the following description taken in connection with the accompanying drawings wherein:

FIG. I is a schematic elevational view of a comber assembly constructed in accordance with the present invention, the comber assembly being shown in a retracted or inactive condition;

FIG. 2 is a schematic elevational view illustrating the comber assembly of FIG. 1 in an operated condition in which it engages a top or upper sheet of a pile of sheets and buckles or bulges the top sheet upwardly to separate the top sheet from the next adjacent lower sheet;

FIG. 3 is a schematic elevational view of the comber assembly after an initial part of an upward or return stroke of the comber assembly during which it is moved from the operated position of FIG. 2 to the retracted position of FIG. 1;

FIG. 4 is a plan view, taken generally along the line M of FIG. 3, further illustrating the structure of a comber assembly; and

FIG. 5 is a schematic elevational view of a second embodiment of the comber assembly.

The present invention provides a comber assembly for use in separating an upper sheet from a next adjacent lower sheet on a pile of sheets. The comber assembly includes a comber member which is mounted on one end of a leaf spring and is moved downwardly into engagement with the upper sheet by a reciprocating drive assembly. Upon continued downward operation of the drive assembly, the spring is deflected and pushes the comber member and the engaged portion of the upper sheet to one side to thereby form a small buckle or rise in the sheet. This small buckle or rise separates the upper sheet from the next adjacent lower sheet at an area where the upper sheet is engaged by a sucker assembly for feeding sheets one at a time.

A comer assembly 10 embodying the present invention is illustrated in FIG. 1 in association with a sucker assembly 12 for feeding sheets one at a time from a pile 14 of sheets. The comber assembly 10 cooperates with the sucker assembly 12 to at least partially separate an upper sheet 18 from the pile 14 by forming a buckle or rise 20 in the upper sheet 14 (see FIG. 2). The buckle 20 is formed before the sucker assembly 12 is operated to apply suction to the upper sheet 14 at the buckle. The formation of the buckle 20 provides a space 22 between the upper sheet 18 and the next adjacent lower sheet 24. This space 22 enables air to enter between the separated sheets 18 and 24 to prevent the lower sheet 24 from being sucked or drawn upwardly with the upper sheet 18 by the wellknown operation of the sucker assembly 12.

In accordance with the present invention, the comber assembly l0 minimizes the formation of shine marks on the upper sheet 18'by minimizing relative movement between a comber member or wheel 28 and a portion of the upper sheet 18 engaged by the comber member. To this end, the comber member 28 is mounted on a free end portion 30 of a leaf spring 32 having an opposite end portion 34 connected to a base member 86. To provide for movement of the comber member 28 into and out of engagement with the upper sheet 18, the base 36 is mounted on a reciprocatable support member or pushrod 40 which forms a part of a suitable drive assembly (not shown). This drive assembly is operated in conjunction with the sucker assembly 12 so that suction is applied to the upper sheet 18 by the sucker assembly 12 only after the comber assembly 10 has been operated to form the buckle or rise 20 in the manner illustrated schematically in FIG. 2.

Immediately before the upper sheet 18 is to be fed from the pile 14, the comber assembly is moved downwardly by the pushrod 40 toward the pile from the inactive or retracted position shown in FIG 1 to a transitory intermediate position similar to that shown in FIG. 3. At this transitory intermediate position, a lower surface portion 44 of the comber member 28 engages a portion 46 of the upper sheet 18. Continued downward movement of the pushrod 40 presses the comber member 28 against the upper sheet 18 and deflects the spring 32 to the position illustrated schematically in FIG. 2. This deflection of the spring 32 causes the comber member 28 to be moved through a combing stroke or distance 50 (FIG. 2) transversely to the direction of the downward stroke of the pushrod 40. During this translational or sideward movement of the comber member 28 through the distance 50, the comber member presses against the upper sheet 18 and pushes the upper sheet to the left (as viewed in FIG. 1) to form the upwardly projecting buckle or bulge 20 (FIG. 2).

To minimize the formation of shine" marks on the upper sheet 18, the comber member or wheel 28 is retained against rotation about an axle 54 as the comber member is moved sidewardly through the combing stroke or distance 50. To this end, a stop member 56 on the comber member or wheel 28 engages a support block 58 to which the axle 54 and free end 30 of the spring 32 are connected. Therefore, when the comber member 28 is moved sidewardly through the distance 50, the stop member 56 engages the support block 58 to prevent counterclockwise rotation of the comber member about the axle 54.

Since the comber member 28 is retained against rotational movement about the axle 54 by the stop member 56, the translational or sideward movement of the comber member 28 through the combing stroke or distance 50 results in the engaged portion 46 of the sheet member 18 being moved through substantially the same distance. Of course, this minimizes movement of the comber member 28 relative to the engaged portion 46 of the upper sheet 18. By minimizing the relative movement between the engaged portion 46 of the upper sheet 18 and the comber member 28, the comber assembly I minimizes the formation of objectionable shine marks on the upper surface of the sheet 18.

As was previously explained, once the buckle 20 has been formed by operation of the comber assembly 10, the suction assembly 12 applies suction to the upper sheet 18 at the buckle 20. The space 22 between the upper sheet 18 and the next adjacent lower sheet 24 enables air to enter between the sheets at the buckle 20 and thereby prevents the lower sheet from being sucked or drawn up against the upper sheet by the operation of the sucker assembly 12. After suction has been applied to the buckle 20 by the sucker assembly 12, the comber assembly is retracted back to the initial position illustrated in FIG. 1. Although this movement of the comber assembly back to the initial position of FIG. I occurs in a quick, single stroke of the pushrod 40, the retraction of the comber assembly may be considered as occurring in two steps during the single stroke of the pushrod 40. During the first step, the comber member 28 is moved from the operated position illustrated in FIG. 2 to a partially retracted transitory position illustrated in FIG. 3.

To further minimize any tendency to form "shine" marks on the upper sheet 18, the comber wheel 28 is rolled along the upper surface of the sheet 18 as the comber assembly 10 moves from the operated position illustrated in FIG. 2 to the partially retracted intermediate position illustrated in FIG. 3. This rolling or rotational movement of the comber member 28 results from a releasing of the spring 32 by an initial upward movement of the pushrod 40 through a distance illustrated schematically at 62 in FIG. 3. As the spring 32 is released and the previous deflection of the spring eliminated, the comber member 28 reverses its previous sideward or translational movement. During the reverse sideward movement, the comber member 28 rolls along the upper sheet 18, in a generally clockwise direction as viewed in FIG. 3. This clockwise rotation causes the stop member 56 to move away from the support block 58 (see FIG. 3). It should be noted that this rotational movement of the comber member or wheel 28 about the axle 54 occurs without substantial slipping between the comber member and the upper sheet 18. Therefore, the portion 46 of the' sheet 18 remains in the position to which it was pushed or shoved by the previous downward stroke of the pushrod 40. This enables the buckle to remain in the sheet even after the comber assembly 10 is partially retracted from the operated position shown in FIG. 2 to the transitory intermediate position shown in FIG. 3.

After the comber assembly 10 has been moved from the operated condition shown in FIG. 2 to the partially retracted condition shown in FIG. 3, continued upward movement of the pushrod 40 lifts the comber member 28 off the upper sheet 18. The comber member or wheel 28 is then rotated in a counterclockwise direction (as viewed in FIG. 3) by a biasing spring 66 (see FIG. 4). This counterclockwise rotation returns the comber member 28 to its initial position wherein the stop member 56 engages the support block 58 (see FIG. 1).

To provide for rotational movement of the comber member of wheel 28 when the comber member is lifted off the upper sheet 18, the biasing spring 66 is connected at one end to a spring block 68 fixedly mounted on the axle 54 (FIG. 4) about which the comber member rotates. The opposite end of the biasing spring 66 is connected, at 72, to the comber member or wheel 28 and urges the stop member 56 into engagement with the support block 58. Of course, the spring 66 is relatively weak so that its biasing influence is easily overcome to enable the comber member or wheel 28 to roll along the upper sheet 18 when the comber assembly 10 is moved from the operated condition of FIG. 2 to the partially retracted or intermediate condition of FIG. 3.

To minimize slipping or a relative movement between the comber member of wheel 28 and the upper sheet 18 when the comber assembly 10 is operated from the retracted condition of FIG. 1 to the operated condition of FIG. 2, the comber member 28 includes a pair of rubber tires or rings 76 (see FIG. 4). These rubber tires or rings have a higher coefficient of friction than does a metallic rim 78 on which the tires 76 are mounted. The relatively high coefflcient of friction of the tires 76 minimizes any tendency of the comber member 28 to slip across the upper surface of the sheet 18 as the comber member 28 is being moved through the combing stroke or distance 50 (see FIG. 2). Of course, the comber member 28 could be provided with a peripheral surface having a relatively high coefficient of friction by means other than the use of the tires 76.

A pin or shaft 82 is mounted on the support block 58 to limit the extent of translational or sideward movement of the comber member 28. Thus, when the comber member 28 has been moved through the desired combing stroke or distance 50 (see FIG. 2) a head portion 84 of the pin 82 engages a stop portion 88 of the base 36 to thereby limit further deflection of the spring 32. By so limiting the deflection of the spring 32, the comber member 28 is retained against further translational movement along the pile 14. To enable the combing stroke or distance 50 to be varied, the pin 82 has a threaded end portion 92 which engages the support block 58 and a lock nut 94. By turning the pin to move the head 84 outwardly from the stop portion 88 of the base 36, the combing stroke or distance 50 through which the comber member 28 is moved is increased. Similarly, by rotating the pin 82 to move the head 84 inwardly toward the stop portion 88 of the base 36, the combing stroke or distance 50 through which the comber member 28 is moved is decreased.

To the end of more fully illustrating the present invention, a second embodiment of the comber assembly is illustrated in FIG. 5. Since the embodiment of the comber assembly illustrated in FIG. 5 includes many elements which are similar to those of the comber assembly illustrated in FIGS. 1-4, numerals similar to those used to designate the elements of FIGS. 1-4 will be used to designate the elements of the comber assembly 100 of FIG. 5. However, to avoid confusion, the suffix letter a will be added to the numerals used in association with the embodiment of FIG. 5.

The comber assembly 100 includes a comber member 28a which is mounted on a free end portion 30a of a leaf spring 32a. An opposite end portion 340 of the leaf spring 320 is fixedly connected to a base 36a which is moved under the influence of a reciprocatable pushrod or support member 40a of a suitable drive assembly (not shown). When the support member is moved downwardly, the comber member 280 is pressed against an upper sheet 18a on a pile 14a of sheets. Continued downward movement of the pushrod 40a results in the spring 32a being deflected in much the same manner as was previously explained in connection with the spring 32 of the embodiment of FIGS. I4. Deflection of the spring 320 causes the comber member 28 to be pushed or shoved sidewardly, toward the left (as viewed in FIG. 5), with a translational movement or combing stroke which forms a buckle or rise 20a in the first sheet 18a.

After the buckle or rise 200 has been formed by the operation of the comber 1 00, a sucker assembly 12a applies suction to the buckle 20a to securely engage the upper sheet 18a. The pushrod 40a is then moved upwardly from the operated position shown in FIG. 5 to a retraCted position (not shown) to reverse the previous translational movement of the comber member 280. It should be noted that a peripheral surface 102 of the comber member 280 will tend to be dragged or moved across the upper surface of the sheet 18a as the comber assembly 100 is retracted. However, since the suction assembly 12a will, by the time the comber assembly 100 is retracted, have applied suction to the buckle portion 20a of the sheet 180, the sheet will not be pulled out of engagement with the sucker assembly 12a.

In view of the foregoing description, it can be seen that the comber assemblies and 1100 include pushrods 40 and 40a which are reciprocated to operate the comber assemblies and thereby forrn'buckles 2t) and 20a in the upper sheets 18 and 118a of the piles of sheets 114 or 14a. The buckles 20 and 20a separate the upper sheets 18 and 180 from the next adjacent lower sheets so that operation of the sucker assemblies 12 and 12a feeds one sheet at a time to suitable apparatus associated with the sucker assemblies. To enable the comber assemblies 10 and 100 to form the buckles 20 and 20a without forming shine marks on the upper sheets 18 and 18a, the comber assemblies 10 and 100 include comber members 28 and 28a which are mounted on free ends 30 and 30a of leaf springs 32 and 32a. Downward movement of the pushrods 40 and 40a causes the springs 32 and 32a to be deflected to thereby effect translational or sideward movement of the comber members 28 and 28a. The comber members 28 and 280 are provided with an outer peripheral surface having a relatively high coefficient of friction so that there is substantially no effective movement between the comber members 28 and 28a and the engaged portion of the upper sheets 18 and 18a during the sideward movement of the comber members.

The operation of the comber assembly 10 has been described herein as involving two effective steps during retraction of the comber assembly from the operated position of H6. 2 to the retracted position of FIG. 1. During the first step, the comber member or wheel 28 is rotated from the operated position shown in FlG. 2 to the partially retracted position shown in FIG. 3 as the pushrod 40 is moved upwardly through the distance 62. During the second step, the comber assembly 10 is lifted upwardly from the partially retracted position of FIG. 3 to the retracted position of FIG. 1. Although it is believed that this is a correct explanation of the operation of the comber assembly R0, the speed at which the comber assembly is operated makes it very difficult to determine exactly what occurs when the comber assembly 10 is moved from the operated position of FIG. 2 to the retracted position of FIG. 1. Therefore, although a particular mode of operation of the comber assembly 10 has been set forth herein, the invention is not to be considered as being limited to any theory as to the particular modeof operation of the comber assembly.

Having described my invention, 1 claim the following:

1. A comber assembly for use in separating one sheet of a pile of sheets from a next adjacent sheet, said comber assembly comprising a base, a leaf spring fixedly connected at one end portion to said base and having a free end portion which is movable relative to said base, comber means fixedly mounted on said free end portion of said leaf spring for movement therewith relative to said base upon deflection of said leaf spring relative to said base, and drive means for moving said base toward the pile of sheets from an initial position in which said comber means is spaced from the pile of sheets to a position in which said comber means engages the one sheet on the pile of sheets and for deflecting said leaf spring relative to said base by continuing movement of said base toward the pile after said comber means has engaged the one sheet to move said free end portion of said leaf spring and said comber means in a direction away from the path of movement of said base through a distance determined by the extent of movement of said free end portion of said leaf spring relative to said base to thereby form a buckle in the one sheet.

2. A comber assembly as set forth in claim 1 further includ- 4. A comber assembly for use in separating one sheet of a pile of sheets from a next adjacent sheet, said comber assembly comprising a base, drive means for moving said base toward and away from he pile of sheets, a rotatable comber wheel, means for operatively connecting said comber wheel to said base for movement therewith relative to the pile, for moving said comber wheel outwardly from said base to an extended position in response to movement of said base toward the pile with said comber wheel in engagement with the one sheet, and for moving said comber wheel inwardly toward said base from the extended position in response to movement of said base away from the pile, and stop means operatively con nected to said comber wheel for retaining said-comber wheel against rotation relative to the one sheet during movement of said comber wheel outwardly toward the extended position to thereby enable said comber wheel to form a buckle in the one sheet and separate it from the next adjacent sheet during the outward movement of said comber wheel to the extended position, said stop means being ineffective to retain said comber wheel against rotation relative to the one sheet during movement of said comber wheel inwardly toward said base from the extended condition so that said comber wheel rolls over the one sheet as said comber wheel moves inwardly toward said base to thereby facilitate maintenance of the buckle in the one sheet.

5. A comber assembly as set forth in claim 4 wherein said stop means includes a nonrotatable stop surface and a stop member operatively connected to said comber wheel for rotation therewith relative to said base, said stop member being disposed relative to said stop surface such that rolling of said comber wheel along the one sheet during outward movement of said comber wheel toward the extended position is prevented by engagement of said stop member with said stop surface during rolling of said comber wheel along the one sheet as said comber wheel moves inwardly from the extended position.

6. A comber assembly as set forth in claim 5 wherein said drive means is operable to move said base away from the pile for a distance sufficient to move said comber wheel out of engagement with the pile, said comber assembly further including spring means for rotating said comber wheel to move stop member into engagement with said stop surface after said stop member has moved away from said stop surface during inward movement of said comber wheel from the extend position and after said comber wheel has moved out of engagement with the pile.

7. A comber assembly as set forth in claim Al wherein said means for operatively connecting said comber wheel to said base includes a leaf spring having one end portion fixedly connected to said base and mounting means fixedly connected to the free end portion of said leaf spring for rotatably supporting said comber wheel.

8. A comber assembly as set forth in claim 4 wherein said comber wheel includes a rim and annular tire means mounted on said rim and having a friction surface for engaging the sheet and retarding relative movement between an engaged portion of the sheet and said comber wheel during outward movement of said comber wheel to the extended position. 

1. A comber assembly for use in separating one sheet of a pile of sheets from a next adjacent sheet, said comber assembly comprising a base, a leaf spring fixedly connected at one end portion to said base and having a free end portion which is movable relative to said base, comber means fixedly mounted on said free end portion of said leaf spring for movement therewith relative to said base upon deflection of said leaf spring relative to said base, and drive means for moving said base toward the pile of sheets from an initial position in which said comber means is spaced from the pile of sheets to a position in which said comber means engages the one sheet on the pile of sheets and for deflecting said leaf spring relative to said base by continuing movement of said base toward the pile after said comber means has engaged the one sheet to move said free end portion of said leaf spring and said comber means in a direction away from the path of movement of said base through a distance determined by the extent of movement of said free end portion of said leaf spring relative to said base to thereby form a buckle in the one sheet.
 2. A comber assembly as set forth in claim 1 further including means operatively interconnecting said free end portion of said leaf spring and said base to limit movement of said free end portion of said leaf spring and said comber means relative to said base.
 3. A comber assembly as set forth in claim 1 wherein said comber means includes a wheel and mounting means fixedly connected to said free end portion of said leaf spring for supporting said wheel for rotational movement relative to said leaf spring.
 4. A comber assembly for use in separating one sheet of a pile of sheets from a next adjacent sheet, said comber assembly comprising a base, drive means for moving said base toward and away from he pile of sheets, a rotatable comber wheel, means for operatively connecting said comber wheel to said base for movement therewith relative to the pile, for moving said comber wheel outwardly from said base to an extended position in response to movement of said base toward the pile with said comber wheel in engagement with the one sheet, and for moving said comber wheel inwardly toward said base from the extended position in response to movement of said base away from the pile, and stop meAns operatively connected to said comber wheel for retaining said comber wheel against rotation relative to the one sheet during movement of said comber wheel outwardly toward the extended position to thereby enable said comber wheel to form a buckle in the one sheet and separate it from the next adjacent sheet during the outward movement of said comber wheel to the extended position, said stop means being ineffective to retain said comber wheel against rotation relative to the one sheet during movement of said comber wheel inwardly toward said base from the extended condition so that said comber wheel rolls over the one sheet as said comber wheel moves inwardly toward said base to thereby facilitate maintenance of the buckle in the one sheet.
 5. A comber assembly as set forth in claim 4 wherein said stop means includes a nonrotatable stop surface and a stop member operatively connected to said comber wheel for rotation therewith relative to said base, said stop member being disposed relative to said stop surface such that rolling of said comber wheel along the one sheet during outward movement of said comber wheel toward the extended position is prevented by engagement of said stop member with said stop surface during rolling of said comber wheel along the one sheet as said comber wheel moves inwardly from the extended position.
 6. A comber assembly as set forth in claim 5 wherein said drive means is operable to move said base away from the pile for a distance sufficient to move said comber wheel out of engagement with the pile, said comber assembly further including spring means for rotating said comber wheel to move stop member into engagement with said stop surface after said stop member has moved away from said stop surface during inward movement of said comber wheel from the extend position and after said comber wheel has moved out of engagement with the pile.
 7. A comber assembly as set forth in claim 4 wherein said means for operatively connecting said comber wheel to said base includes a leaf spring having one end portion fixedly connected to said base and mounting means fixedly connected to the free end portion of said leaf spring for rotatably supporting said comber wheel.
 8. A comber assembly as set forth in claim 4 wherein said comber wheel includes a rim and annular tire means mounted on said rim and having a friction surface for engaging the sheet and retarding relative movement between an engaged portion of the sheet and said comber wheel during outward movement of said comber wheel to the extended position. 